1. Field of the Invention
The present invention relates to an ink jet recording head, a method of manufacturing it and an ink jet recording device.
2. Description of the Related Art
Recently, an ink jet recording device is drawing attention as a low-cost quality color recording device. A head chip which is an ink jet recording head is fastened to the end of the ink jet recording device and ink droplets are jetted from the head chip.
As shown in FIGS. 14B and 14C and FIG. 15, in a head chip 100, plural individual passages 102 communicating with each nozzle 104, a common liquid chamber 106 communicating with each individual passage 102 and a communicating port 110 for supplying ink to the common liquid chamber 106 from an ink tank and others are formed.
The head chip 100 is formed by joining a passage substrate 120 (see FIG. 16C) in which the individual passage 102, the common liquid chamber 106 and others are formed and a heater element substrate 126 (see FIG. 16A) in which a heater element 108, a signal processing circuit 122 for driving the heater element 108 and a driver circuit 124 are formed.
Referring to FIGS. 16, a method of manufacturing the head chip 100 made up as described above in a conventional example will be described below.
Technique for isolating into a chip to be a head chip after two silicon substrates for example are joined with a resin layer between them is disclosed in Japanese Published Unexamined Patent Application No. Sho 61-230954.
The heater element substrate 126 can be formed using LSI manufacturing technology and LSI manufacturing facilities for example. First, as shown in FIG. 16A, a heater layer to be a heat storage layer and a heater element, a protective layer for preventing the heater element 108 from being damaged by the pressure of bubbles generated by the heat of the heater element and others are laminated on a monocrystalline silicon wafer 128. Next, for a protective layer against ink, a resin layer 130 such as photosensitive polyimide is laminated. An opening (not shown) for at least the heater element 108 and an electric signal input-output terminal 132 is provided to the resin layer 130. Further, to form the individual passage 102 and a part of the common liquid chamber 106, a second resin layer 131 is formed as shown in FIG. 16B.
In the meantime, for forming the passage substrate 120, first, grooves 106A and 102A to be the common liquid chamber 106 and the individual passage 102 are formed on a silicon wafer 133 having a crystal face of  less than 100 greater than  by, for example, anisotropic etching (see FIG. 16C). For forming the grooves 106A and 102A by anisotropic etching, as described in Japanese Published Unexamined Patent Application No. Hei 11-245413 and Japanese Published Unexamined Patent Application No. Hei 6-183002, after an etching mask is patterned on the silicon wafer 133 which has a crystal face of  less than 100 greater than  on the surface, the grooves 106A and 102A can be precisely formed by etching using heated aqueous solution of potassium hydroxide (KOH).
Further, an adhesive 135 thinly applied on a film by spinning coating and others is selectively transferred on a convex portion of a composition plane on which the grooves 106A and 102A are formed for the silicon wafer 133 using a method proposed in Japanese Published Unexamined Patent Application No. Sho 63-34152 and others as shown in FIG. 16D.
Next, the silicon wafer 128 and the silicon wafer 133 are precisely aligned using an alignment mark 150 provided in units of wafer by a substrate aligner so that the heater element 108 and the groove 102A for the individual passage 102 are opposite and are heated at approximately 200xc2x0 C. for four hours, applying pressure by a vacuum heating and pressure device. As a result, the applied adhesive 134 is cured, and the silicon wafer 128 and the silicon wafer 133 are bonded as shown in FIG. 16E.
Further, a bonded body 156 in which the silicon wafer 128 and the silicon wafer 133 are bonded is diced and isolated in units of chip by a dicing method described in U.S. Pat. No. 2,888,474 and multiple head chips 100 are simultaneously manufactured as shown in FIG. 16F.
In this case, as shown in FIG. 14A, first, an opening 142 is formed in the silicon wafer 128 by machining along a dicing line 140. As a result, the electric signal input-output terminal 132 formed on the silicon wafer 128 (the heater element substrate 126) is exposed outside as shown in FIG. 17. Next, the length of the individual passage 102 (the nozzle) in each head chip 100 is provided by machining the bonded body 156 along the dicing line 144. Finally, the bonded body is diced and isolated into an individual head chip 100 by machining the bonded body 156 along the dicing line 146.
In the head chip 100 formed as described above, as shown in FIGS. 14B and 14C and FIG. 15, the cut-out portion 134 is formed at the back 120B on the reverse side to a nozzle forming plane 120A on which nozzles 104 are formed in the passage substrate 120 and the electric signal input-output terminal 132 formed on the heater element substrate 126 is exposed outside from the opening of the resin layer 130.
The head chip 100 formed as described above is fastened to a heat sink 136 for outgoing radiation as shown in FIG. 15. A printed wiring substrate 138 is also formed on the heat sink 136, power and a signal supplied from the body of the ink jet recording device are transmitted to the heater element substrate 126 via a bonding wire 141, and a signal and others from various sensors provided to the heater element substrate 126 are transmitted to the body of the recording device.
As shown in FIGS. 18, in the head chip 100, if the electric signal input-output terminal 132 is formed at both ends in a nozzle arrangement direction (the longitudinal direction of the chip) in which the nozzles are arranged, dicing along a dicing line 154 for forming the cut-out portion is performed in addition to dicing along a dicing line 152 for dicing the head chip and isolating into each chip as dicing along the shorter direction of the chip so as to expose the electric signal input-output terminal 132 at both ends.
As described above, in a method of manufacturing the head chip 100 in the conventional example, the electric signal input-output terminal 132 is exposed outside by machining the passage substrate 120 in which the grooves are formed by dicing. Therefore, the shape of the cut-out portion (the exposed part) is linear and there is a problem that the shape of the cut-out portion (the exposed part) 134 of the head chip 100 is limited. That is, there is a problem that not only the arrangement of the electric signal input-output terminal 132 but the inside structure of the chip are restrained depending upon the shape of the cut-out portion 134.
Also, as shown in FIG. 18B, if the cut-out portion 134 for the electric signal input-output terminal 132 is formed at both ends in the longitudinal direction (the nozzle arrangement direction) of the head chip 100, the electric signal input-output terminal 132 is exposed on the side of the nozzle forming plane 120A and there may occur a problem that a hydrophobic agent adheres to the electric signal input-output terminal 132 by hydrophobic treatment for the nozzle forming plane 120A to disable electric connection. Also, in a process for sealing the electric signal input-output terminal 132, there may occur a problem that sealer is forced out from the electric signal input-output terminal 132 to the nozzle forming plane 120A.
The present invention has been made to solve the problems and provides an ink jet recording head in which the degree of freedom in the design of the arranged position of an electric signal input-output terminal is enhanced, its manufacturing method and an ink jet recording device.
According to an aspect of the present invention, the ink jet recording head which is formed by laminating a first substrate and a second substrate and inside of which an ink jetting mechanism is mounted includes a nozzle forming plane of the first substrate having a nozzle for jetting ink, a cut-out plane of the first substrate defining a cut-out portion at an end thereof, the cut-out portion not penetrating the substrate, and the cut-out plane being opposite to the nozzle forming plane, and an electric signal input-output terminal for electrically connecting to an external device, the terminal being formed on the second substrate at a face joining to the first substrate. The electric signal input-output terminal is exposed to the outside by forming the cut-out portion and is surrounded by facets forming the cut-out portion.
Since the electric signal input-output terminal is exposed outside by the cutout portion formed at the back of the nozzle forming plane in the first substrate, electric connection to an external device is facilitated.
In addition, the electric signal input-output terminal is surrounded by the facets forming the cut-out portion at the back of the nozzles and it is possible to securely prevent a hydrophobic agent from adhering to the electric signal input-output terminal when hydrophobic treatment is applied to the nozzle forming plane to result in electric connection failure.
According to another aspect of the present invention, the ink jet recording head which is formed by laminating a first substrate and a second substrate and inside of which an ink jetting mechanism is mounted includes a nozzle forming plane of the first substrate having a nozzle for jetting ink, a side plane continuing to the nozzle forming plane, the side plane defining a cut-out portion leaving a region continuing to the nozzle forming plane, and an electric signal input-output terminal for electrically connecting to an external device, the terminal being formed on the second substrate at a face joining to the first substrate. The electric signal input-output terminal is exposed to the outside by forming the cut-out portion.
As the electric signal input-output terminal is exposed outside by the cut-out portion formed on the side continuing to the nozzle forming plane in the first substrate, electric connection to an external device is facilitated.
In addition, since the cut is formed with the region left at least on the side of the nozzle forming plane on the side continuing to the nozzle forming plane in the first substrate, it is possible to securely prevent a hydrophobic agent from adhering to the electric signal input-output terminal to result in electric connection failure when hydrophobic treatment is applied to the nozzle forming plane.
According to another aspect of the present invention, a method of manufacturing an ink jet recording head in which plural ink jet recording heads are simultaneously manufactured using a wafer includes the steps of forming a through-hole together with a nozzle in a first area of a first wafer equivalent to a chip, joining a second wafer, provided with an electric signal input-output terminal in a second area equivalent to a chip, with the first wafer, and exposing the electric signal input-output terminal to the outside from the through-hole, and dicing and isolating a joined body composed of the first wafer and the second wafer in units of chip.
First, the ink jet recording head in which the electric signal input-output terminal is exposed outside can be efficiently manufactured by forming the through-hole to be a cut-out portion together with nozzles in the first area equivalent to a chip of the first wafer, joining the second wafer where the electric signal input-output terminal is formed in the second area equivalent to a chip and the first wafer and dicing and isolating the wafers into each chip. At this time, since the through-hole to be a cut-out portion is formed in the first area of the first wafer, dicing for forming the cut-out portion in the dicing and isolating process is not required and the manufacturing efficiency is enhanced.
In addition, since the through-hole to be a cut-out portion can be formed in the first area of the first wafer by a method different from dicing such as etching and laser beam machining, the cut-out portion can be formed in a desired position of the head so that it has a desired shape. That is, the degree of the freedom of design in the ink jet recording head is enhanced.
According to another aspect of the present invention, a method of manufacturing an ink jet recording head formed by laminating a first substrate having an individual passage for supplying ink to a nozzle, a common liquid chamber communicating with the individual passages and a through-hole for leading ink from the outside to the common liquid chamber and a second substrate in which a heater element opposite to the individual passage is formed, includes the steps of forming a groove not pierced from a first surface of the first substrate to a second surface on the reverse side by etching, and piercing the groove by thinning the substrate by etching or grinding from the second surface to form the through-hole in the common liquid chamber.
When the through-hole is formed in the first substrate, the strength of the first substrate is deteriorated, the handling of the first substrate becomes difficult and the first substrate may be broken. Then, in the invention, if a communicating port is provided to the common liquid chamber by grinding and others as a final machining process of the first substrate after the individual passage and the groove for a part of the common liquid chamber are simultaneously processed, the breakage and others of the substrate can be prevented.
Also, when a through-hole is formed in the first substrate before the individual passage is formed, gas for cooling leaks from the second surface to the first surface in processing the individual passage and the processing quality and the precision of the individual passage are deteriorated. Then, in the invention, the processing quality and the precision of the individual passage can be enhanced by forming an opening in a part of the common liquid chamber by thinning the substrate from the second surface after the individual passage is processed.